Identification of TIA-1+ and Granzyme B+ Cytotoxic T Cells in Lichen sclerosus et atrophicus

BACKGROUND: The onset and persistence of cutaneous lichen sclerosus et atrophicus (LSA) are linked to the presence of an inflammatory infiltrate of CD3+ T cells that includes CD4+ and CD8+ cells. The functional relevance of the presence of these cells is unknown. OBJECTIVE: The study intended to quantify resting and activated cytotoxic T cells in LSA lesions. METHODS: Twenty patients with active LSA were studied. Skin-infiltrating T cells were immunohistologically characterized with antibodies against CD3, CD8, T-cell-restricted intracellular antigen (TIA-1) and granzyme B (GrB). TIA-1 labels cytotoxic granules of resting and activated T cells, whereas GrB designates activated cytotoxic T lymphocytes (CTL). RESULTS: In all cases, numerous T cells were consistently found expressing cytotoxic granules. The results indicated a high number of infiltrating CD8+ TIA+ T cells. Furthermore, a notable number of GrB+ activated CTL associated with hydropic degeneration of the basal cell layer were found within the dermal infiltrate and at the dermoepidermal interface. CONCLUSION: This study shows that a high proportion of skin-infiltrating T cells in LSA has a potential cytotoxic function. The results indicate that hydropic degeneration of basal keratinocytes may at least partially be mediated by CTL-dependent mechanisms. Our data also indicate that a cell-mediated immune response may play an important role in the pathogenesis of the disease.